The present invention relates to automatic packaging machines. In particular, the present invention concerns a device, which is joined to a machine for packaging products in related box-like containers, and which is capable of folding vertical flaps of the containers during the container closure steps.
It is known that machines for packaging products in box-like containers withdraw cyclically a flat folded tubular blank from a suitable magazine and erect it, so that it becomes a container. Then these machines place the obtained container on a packaging line, which moves stepwise horizontally and in a determined direction, with a predefined rate.
On a parallel way, the products to be packaged, usually already pre-packaged in blister packs, vials or others, are carried to a working station, in step relation with the forward motion of the boxing line. Then the products are introduced into related containers by pusher means.
In this step, a typical container is opened at both ends, which are situated on opposite sides with respect to the above mentioned forward motion direction.
Each of the apertures formed by the open ends features a pair of vertical flaps, later on called fore flap and rear flap with respect to the above mentioned forward motion direction, and a horizontal flap.
After having been folded, these flaps define the container opposite head walls.
Usually, in order to facilitate the introduction of the products into the container, the latter is situated on the packaging line in such a way that the horizontal flap of the introduction aperture extends from the upper aperture edge.
Generally, the container flaps are closed according to a predetermined sequence by suitable devices, which gradually fold the flaps and bring them close to the container body.
In particular, the flaps of the aperture opposite to the products introduction one are closed upstream of the products introduction station, while the flaps of the products introduction aperture are closed downstream of the above mentioned forward motion direction.
Various known devices have been used so far for closing the vertical flaps.
According to the operation steps of some devices, the fore flap of the container, while moving, strikes a stationary stop, which folds the fore flap and keeps it in the folded position, against the flap tendency to return to its original position due to the elastic reaction, until another closing member, of known type, folds also the horizontal flap.
The rear flap is closed by a hinged protruding arm, which folds the rear flap before it reaches the stationary stop and keeps it in the folded position until the outer edge of the rear flap is taken under control by the stop.
The above described solution is relatively simple, but it is not very convenient when the container size must be changed. Actually, in this case, the hinged arm must be moved towards upstream, or downstream, in a very precise way, according to the flap size change.
Also the hinged arm size must be changed according to the flap size change.
Moreover, the vertical position of the arm must be set taking into consideration not only the vertical flap width, but also the possible presence of the horizontal flap journaled to the aperture upper edge.
Another know device for closing vertical rear flaps includes a disc, situated beside the packaging line and featuring a suitably shaped cavity.
The disc is driven into rotation in step relation with the container movement, so that the flap enters the above mentioned cavity.
At this point, the cavity edge folds the flap. The above described device folds correctly flaps of different width. However, in case of size changeover, the device must be positioned at different distances from the stationary stop accordingly. Moreover, the device vertical position must be changed in relation to the different heights of the flaps of containers of different size, as well as in relation to possible presence of the horizontal flap hinged to the container upper wall.
Another closing device includes a plurality of discs, situated one over another. However, this device does not solve the problem due to the every-time-different distance from the stationary stop and to the presence of the horizontal flap hinged to the container upper wall.
Another drawback of known folding devices results from the way in which they act on the flaps, rather jerky, sharp movements, which can sometimes damage the flaps.
From documents xe2x80x9cPATENT ABSTRACTS OF JAPAN, vol. 014 no. 209 (M-0968), Apr. 27, 1990 and JP-A-02 045304 (MITSUBISHI HEAVY IND LTD)xe2x80x9d a device is known which folds side flaps of boxes being filled. To omit an adjustment work of a side flap tucker every size-change, an end of a L-like stacker body, forming a flap pusher, is supported slidably with a link and is connected, at a middle part, to a circulating lever. When le lever rotates, the joining point between the stacker and the link reciprocates over a circumference arc and the flap pusher at the front of the stacker follows the box movement for a short time while folding the flap. When the flap length is altered, the flap tucker is not to be adjusted like in conventional cases.
The object of the present invention is to propose a device for closing vertical flaps of a container, e.g. a box-like container, moved along a packaging line, a device which does not present the above mentioned drawbacks and can work with containers of different size, equipped with different flaps.
Another object of the present invention is to propose a device, which can be used also with containers having horizontal flaps situated in the lower wall, independently from the container size.
A further object of the present invention is to propose a device which is able to fold the rear flaps with a gradual movement, preventing the container from stresses and pushes, thus without leaving traces of the folding operation.
Still another object of the present invention is to propose a simple and strong device, which is completely reliable and does not provoke or sustain damages even in case of loss of working synchronism.
The above mentioned objects are obtained, in a device for folding vertical flaps of box-like containers being moved in a forward direction along a line for packaging products into the containers, with each container including at least one fore vertical flap and at least one rear vertical flap, which are to be folded toward the inside of a corresponding aperture of the container, so as to define respective head walls of the container, including:
at least one stationary striker situated beside said packaging line and in a path of said aperture, for intercepting said fore vertical flap while said container is moving and for folding said fore flap toward the inside of said aperture;
folding means for folding said rear vertical flap, situated upstream of said stationary striker with respect to said forward direction, said folding means moving cyclically along a trajectory including at least one first part, in which said folding means move close to said container, and at least one second part, in which said folding means touch said rear flap and fold it toward inside of said aperture, said first part being substantially perpendicular to said forward direction, upstream of said rear flap, and said second part being substantially parallel to said forward direction an concordant therewith;
supporting and operating means for supporting and guiding said folding means along a circumference arc concentric with a first axis;
trajectory correcting means guided by said folding means for constraining said folding means while rotating about a second axis, said second axis being substantially parallel to said first axis, with a combination of a shift and rotation movements causing said folding means follow said trajectory;
transmission means, aimed at moving said operating means in step relation with the packaging line forward movement.